Method for the treatment of scars and keloids

ABSTRACT

A method and a pharmaceutical composition for non-topical wound, scar and keloid treatment is described which contains cross-linked glycosaminoglycans and conventional pharmaceutical auxiliary and/or carrier substances. The pharmaceutical composition is preferably administered intralesionally e.g. by injection in the form of a gel containing water. The cross-linked glycosaminoglycans are also suitable for use as cosmetics and skin care products.

This is in an application under 35 U.S.C. §371 of PCT/EP92/02990 havingan international filing date of Dec. 24, 1992.

BACKGROUND OF THE INVENTION

The invention concerns a pharmaceutical composition for the treatment ofwounds, scars and keloids.

Excess new growth of scar tissue occurs in many people during healing ofskin wounds. In medical terminology this new formation of tissue isreferred to as cicatricial hypertrophy or as keloid in severe cases.These are unpredictable reactions during wound healing caused by apredisposition. Up to now the reasons for excess cicatrisation are notknown. Thus at present there is also no scientifically based causalmethod of treatment.

Numerous methods have been described for keloid treatment (cf. e.g.McCarthy/Convers "Plastic Surgery", volume 1, pages 732-747, W. B.Saunders, 1990). However, they are all more or less empirically basedand do not have a secure foundation in a strict scientific sense. Thisis due on the one hand to a lack of basic knowledge and is also due tothe fact that a spontaneous tendency of untreated keloids to regress isoften observed.

As a consequence there is an extremely large number of competing methodsof treatment whose effectiveness is, however, doubtful and of which themost important are briefly described in the following.

It is necessary to differentiate between mechanical (physical) andmedicinal (chemical) methods of treatment.

The mechanical methods of treatment encompass the application ofpressure on the keloid by external compression bandages and theapplication of foils made of silicon elastomers. A major disadvantage inthis case is that the application has to be carried out over months andyears. It can also not be used to the same extent in all body regions;thus for example an adequate degree of compression cannot be achieved onthe neck. In addition extensive compression bandages always mean aconsiderable restriction in the freedom of movement and quality of lifefor the carrier. Moreover they also create considerable problems ofhygiene, in particular in the warm period of the year and in hotcountries. Compression bandages can also again lead to renewed tissuelesions by the mechanical strain on the sensitive scar skin and thusagain promote keloid formation.

The physical methods also include cold treatment (cryotherapy) and lasertherapy. Both methods produce tissue necroses by cold or heat by whichmeans the active connective tissue cells and the fibrous substancewithin the keloid are destroyed. The keloids temporarily collapse andtissue defects are formed. During the subsequent healing of thesedefects, connective tissue cells again immigrate by which means theformation of keloid starts again. Consequently this method of treatmentcan thus always only achieve short-term improvements but no finalhealing.

In the case of the medicinal methods it is necessary to differentiatebetween preparations for external application and for injection.

In the case of the agents for external application, these are usuallyointments with a great variety of active substances such as e.g.hormones, amino acids, mucopolysaccharides. Plant extracts such as fromthe thorn-apple are also used. A preferred component of preparations forthe external treatment of scars and cicatricial keloids is heparin (cf.e.g. "Pharmazie in unserer Zeit" 10 (1981), page 168 to 181).

All preparations of active substances for external applications have thesame inherent disadvantage, namely that the external application, i.e.spreading on the skin over the keloid, does not ensure an adequatetissue concentration in the keloid itself which can reach a thickness ofup to several centimetres. Due to the excessively increased bloodcirculation within the keloids, the active substances--provided thatthey can penetrate the skin barriers at all--are rapidly transportedaway via the blood and lymph stream. The diffusion of the activesubstances in the tissue therefore only plays a subordinate role in thedistribution.

It is also known that the active substance heparin cannot penetrate theepidermal layers. Thus the effect of externally applied preparations,such as e.g. ointments based on heparin, on connective tissue cells isdoubtful. It cannot therefore be excluded that the successes achievedwith scar ointments containing heparin could be ascribed to spontaneoushealing.

Derivatives of the hormone cortisol (hydrocortisone) are used in theinvasive methods of treatment for keloids; due to the known increasedblood circulation within keloids and the concomitant rapid transport ofpharmaceutical agents, the crystalline poorly soluble forms arepreferably used with which a depot effect can be achieved. Sincecortisol and its derivatives strongly inhibit the cells of connectivetissue, the quantitatively and qualitatively strongest changes inkeloids can be achieved at present with the invasive administration(injection) of pharmaceutical preparations based on crystallinecorticoids (corticosteroids).

However, a decisive disadvantage of this therapy with corticoids is thelack of control of the reaction. Therefore in the practical applicationthis can either result in an undesired scar atrophy i.e. a divergenceand sinking of the scar with corresponding disfigurement or in aninadequate reaction of the tissue with an unsatisfactory therapeuticresult.

A further disadvantage of corticoid therapy is the systemic action ofthe dissolved active substance which prevents its use in the case ofkeloids of large area or in children.

SUMMARY OF THE INVENTION

The object of the invention is to provide a pharmaceutical compositionfor the treatment of wounds, scars and keloids with which theaforementioned disadvantages that occur in previous methods of treatmentcan be avoided, in particular the undesired side-effects of corticoidtherapy such as e.g. local over-reactions, that can be administeredeasily and successfully and is degraded by the organism.

This object is achieved by the pharmaceutical composition of theinvention which contains cross-linked glycosaminoglycans andconventional pharmaceutical auxiliary and/or carrier substances.

Practical embodiments thereof are the subject matter of this invention.

A further subject matter is also a process for the production of thepharmaceutical compositions according to the invention.

It is possible using the compositions according to the invention toavoid the undesired properties of corticoid therapy. Namely it was foundthat the cross-linked glycosaminoglycans (GAG, mucopolysaccharides) usedaccording to the invention have an inhibitory effect on keloid formationwhen they are administered non-topically (intralesionally). In this caseno local over-reactions occur as is the case with the corticoids andalso no systemic effects. A further advantage is the biologicaldegradability in the organism.

Moreover the compositions according to the invention also allow thesuccessful treatment of deep scar formations in connective tissue suchas e.g. Dupuytren's disease of the palmar surfaces or the so-calledInduratio penis plastica (IPP) which form without prior injury(cross-section).

DETAILED DESCRIPTION OF THE INVENTION

Cross-linked glycosaminoglycans according to the invention areunderstood to be those in which two or several of the same and/ordifferent glycosaminoglycans are linked together to form a molecularunit. The cross-linking is preferably carried out by chelate formation,complex formation and/or salt formation and in particular by a chemicalcross-linking.

Natural or synthetic glycosaminoglycans and also substances that arechemically related thereto can be used as glycosaminoglycans. They canbe of an anionic or cationic character.

Natural glycosaminoglycans that are preferably used are those that occurin human connective tissue in particular e.g. hyaluronic acid, heparin,heparin sulfate, chondroitin sulfate. Sulfated polysaccharides arepreferably used as synthetic glycosaminoglycans. Substances that arechemically related to glycosaminoclycans that are used according to theinvention are preferably those of biological origin and in particularchitosamine and chitosan or their derivatives such as e.g.N-carboxybutlychitosan (cf. R. Muzzarelli et al., Carbohydrate Polymers11 (1989) 307-320). The formation of chelates, poorly soluble salts orcomplexes of glycosaminoglycans which also represent a cross-linkingwithin the sense of the invention is achieved by a holding-togetherthrough ionic forces as is common for such chelates, salts or complexes.

The cross-linked glycosaminoglycans used according to the invention canbe produced in a well-known manner. The chemical cross-linking in thisprocess is usually carried out by cross-linking with bifunctionalreactive agents such as e.g. glutaraldehyde or carbodiimide; it is,however, also for example possible to produce cross-linking via amidebonds by means of bifunctional amino acids such as lysine, protamines oralbumins. If glycosaminoglycans or analogues thereof that have beenproduced synthetically are used according to the invention then thesecan already be primarily cross-linked during production so that afurther treatment for cross-linking is not necessary. Suchglycosaminoglycans are partly commercially available already in across-linked state and can be used directly according to the invention(e.g. "Hylon" and "Hylagel", a cross-linked hyaluronic acid from theBiomatrix Company NJ, USA; for the production c.f. also U.S. Pat. Nos.4,713,448, 4,605,691).

It is preferable to cross-link identical glycosaminoglycans arepreferably and then use them according to the invention but it is alsopossible according to the invention to use a combination of two or moredifferent or partially different glycosaminoglycans. In a particularlypreferred embodiment, glycosaminoglycans with an extremely long chain(molecular weight preferably between 100,000 and 1,000,000) are used; inthis case the degree of cross-linking can then remain low. The productsare practically free of protein.

In a particularly preferred embodiment of the invention intermolecularlycross-linked heparin is used as the cross-linked glycosaminoglycan.

The intermolecular cross-linking of heparin can for example be carriedout in the following manner: commercially available heparin is treatedwith dilute nitric acid by which means reactive aldehyde groups areformed on the heparin; subsequently a reductive animation is carried outby means of NaBH₃ CN. Covalent bonds are formed between the individualheparin chains (end and side chains) via the free amino functionalgroups of heparin.

A cross-linking of heparin by complex formation is preferably carriedout with protamines, gentamycin or vancomycin, metal ions such as e.g.Fe²⁺, Zn²⁺.

The pharmaceutical compositions according to the invention contain thecross-linked glycosaminoglycans preferably in amounts of 0.1 to 20% byweight in relation to the total pharmaceutical composition and inparticular in an amount of 0.5 to 10% by weight and especiallypreferably in an amount of 1 to 5% by weight.

The pharmaceutical compositions according to the invention can bepresent in the form of preparations that can be administeredintralesionally and in particular in the form of injectable gelspreferably with a water content of 80 to 99% by weight and also as ananhydrous precursor e.g. lyophilized powder in the form of a powder. Thepharmaceutical auxiliary and carrier substances that can be used arethose that are conventionally used for this purpose and are suitable forthe application according to the invention and are compatible with thecross-linked glycosaminoglycans. The preferred carrier substance iswater.

The pharmaceutical compositions according to the invention can forexample contain agents to set the pH value, stabilizers, antioxidants,solubilizers, agents that promote penetration, preservatives and/or gelformers as pharmaceutical auxiliary substances as they are usually usedin such compositions. They are used in the usual amounts for suchpreparations.

The pharmaceutical compositions according to the invention can inaddition to the actual active substances (cross-linkedglycosaminoglycans) also contain further pharmaceutically activesubstances that are compatible with the cross-linked glycosaminoglycanswithin the scope of the application e.g. active substances for thetherapy of skin diseases (dermatoses), antibiotics (in particularantibiotics with a charge of opposite polarity such as e.g. gentamycinand vancomycin with a positive charge for e.g. cross-linked heparin, ore.g. penicillins or cephalosporins with a negative charge for e.g.cross-linked chitosamine), sulfonamides, disinfectants, hormones (e.g.corticoids) and hormone derivatives (e.g. cortisol), local anaestheticse.g. of the lidocaine or novocaine type, vasoactive substances forvascular constriction (avoidance of bleeding), adrenalin, enzymes suchas e.g. hyaluronidase, interleukins, growth factors e.g. EGF, PDGFand/or IGF, skin care agents and/or agents that stimulate blood flow(hyperaemising agents). These substances can be present bound firmly tothe glycosaminoglycans such as e.g. antibiotics with a heteropolarcharge of opposite polarity i.e. as a component of the cross-linkedglycosaminoglycans and are then released during the degradation of thecross-linked glycosaminoglycans or they can be released by a controlledrelease type of system.

In the preferred application according to the invention in the form ofan injection, the preparations can for example contain localanaesthetics to avoid pain when the injection cannula is inserted. Thepreparations preferably contain an anionically or cationically chargedmolecule such as gentamycin as an antibiotic which is bound as acounter-ion to the cross-linked glycosaminoglycans and thus remainsimmobilized in loco which prolongs the action accordingly.

The compositions according to the invention can be produced in aconventional, generally known manner for the production of suchcompositions. In this process the order of mixing of the individualcomponents is usually not critical.

The invention also concerns a process for the production of thecompositions which is characterized in that the cross-linkedglycosaminoglycan and the other components are dissolved in thepharmaceutical carrier. Water is preferably used as the pharmaceuticalcarrier and it is expedient to carry out the process while heating andsubsequently cooling. For protection against oxidation it may beexpedient to work under an inert gas atmosphere in particular undernitrogen.

The type, dose and frequency with which the composition according to theinvention is administered depends in particular on the severity of thedisease and the general state of the patient and also quite generally onthe state and the sensitivity of the skin scar. If the compositionsaccording to the invention are administered in the form of preparationsthat can be applied topically then the administration is as a rule inaccordance with the usual conditions for such compositions.

The type of treatment and frequency of administration also depends inparticular on the individual response of the person to be treated. Anapplication of gels is preferably carried out at intervals of 1 to 2months.

If the compositions according to the invention in the form of injectablegels are applied intralesionally which is primarily the case then thisis preferably carried out by injection with the aid of fine cannulae andwith pressure-resistant syringes. The gels according to the inventioncan also be shot percutaneously with the aid of compressed airinstruments; compressed air instruments such as those that are known inmedicine for such an application can be used for this.

In a particularly preferred embodiment of the invention thepharmaceutical preparation in the form of an injectable gel containscross-linked heparin as the cross-linked glycosaminoglycan. Whereas forexample the injection of non-cross-linked heparin does not come intoconsideration because heparin inhibits blood coagulation and isadditionally rapidly transported out of the lesion via the vascularsystem and then has a systemic effect similar to the corticoids, heparinloses its inhibitory properties on blood coagulation in the cross-linkedform according to the invention and cannot be transported away via theblood and lymph stream. It therefore remains active at the site ofapplication in the keloid tissue for weeks and months after injection.Degradation is primarily via phagocytosis by special cell populations.

When the compositions according to the invention are used which containcross-linked glycosaminoglycans there is also no occurrence of localover-reactions and no systemic effects such as is the case forcorticoids. A further advantage is the biological degradability in theorganism. Thus for example the intralesional application by injectioncan be repeated at intervals of 4 to 8 weeks.

An advantage of the preferred preparations according to the invention inthe form of injectable gels and their intralesional application is alsothat no additional hygienic measures whatsoever are necessary after theinjection sites have healed. All regions of the body can be treated inthe same manner and the mobility of the patients is not restricted bybandages. Treatment with the preparations according to the invention canalso prevent an occurrence or reoccurrence of keloids which demonstratesits preventive effect.

The invention therefore also concerns the use of cross-linkedglycosaminoglycans for the treatment of wounds, scars and primarilykeloids and for the production of a pharmaceutical composition forwound, scar and keloid treatment. In this case the aforementionedglycosaminoclycans that were stated as being preferred are preferablyused as the cross-linked glycosaminoglycan.

A particular method of application for the prevention of keloids orcontract scars is the administration of anhydrous precursors ofcross-linked glycosaminoglycans (e.g. as a lyophilisate) in the form ofa wound powder into fresh wounds. In this case the powder is sprinkledinto the open wound or wound cavity before wound closure. The wound isthen closed by a suture, clamps etc.. In the wound the powder takes upwater from the tissue and then corresponds to the preparation accordingto the invention in the form of a gel or itself represents a preparationaccording to the invention.

The powder or gel form can also be introduced into large body cavitiesto prevent undesired adhesions e.g. into the abdominal cavity orthoracic cavity during a surgical operation on the intestine or thelung, into the pericardium, or after operative procedures via indwellingdrainages. In the case of inflammatory effusions into large bodycavities, the preparation according to the invention can also beintroduced via the indwelling cannula after puncturing and emptying theeffusion.

The preparation according to the invention which may be on a suitablecarrier (e.g. tampon) can also be introduced into cavities and ducts ofthe body that are accessible from the outside e.g. into the main nasalcavities and paranasal sinuses or into the meati of the nose or into thetear ducts to prevent scarred adhesions.

It is known from U.S. Pat. No. 4,605,691 that cross-linked gels ofhyaluronic acid can be use alone or together with other hydrophilicpolymers in cosmetic formulations. R. Muzzarelli et al. (1.c) alsodescribe the use of N-carboxybutylchitosan for cosmetic preparations.

It was now surprisingly found that the cross-linked glycosaminoglycansaccording to the invention that are described above are excellentlysuitable as a carrier or component of cosmetics and skin care products.

The present invention therefore also concerns the use of thecross-linked glycosaminoglycans described above with the exception ofcross-linked hyaluronic acid or cross-linked N-carboxybutylchitosan forcosmetics or as skin care products. In particular the cross-linkedglycosaminoglycans that were previously stated as being preferred anddistinctively described are used for this.

The cosmetic preparations and skin care products can be present in theusual forms for such preparations e.g. as creams, ointments, lotions andin particular as gels that can be applied topically. They can alsocontain other auxiliary and/or carrier substances that areconventionally used for this that are compatible with the cross-linkedglycosaminoglycans according to the invention. In addition they can alsocontain the auxiliary substances and/or further active substancesdescribed previously in connection with the pharmaceutical preparations,provided that they are compatible with the cross-linkedglycosaminoglycans within the scope of the application and arepractical.

It is intended to elucidate the invention in more detail by thefollowing examples without limiting it thereto.

EXAMPLE 1

Production of an injectable gel from the following components:

    ______________________________________                                        Component                Amount                                               ______________________________________                                        cross-linked hyaluronic acid                                                                           0.004 g                                              ("Hylagel" Biomatrix Co., NJ, USA)                                            lidocaine hydrochloride  0.02 g                                               water, purified                                                               (DAB 9)                  to 1.0 g                                             ______________________________________                                    

The components are dissolved under a nitrogen atmosphere while stirringand briefly heating; a colourless clear gel is obtained after cooling;pH value: 7.00±0.1.

The gel is dispensed into pressure-resistant piercable ampoules andsealed. Afterwards a heat sterilization is carried out and the gel isstored protected from light.

Application example 1

The treatment of a ca. 3 cm×5 cm dark-red raised keloid is describedwhich was present on the back of a 30 year old woman after a tangentialcut by a broken pane of glass.

The patient complained about itching in the area of the keloid. Thekeloid was infiltrated with cross-linked hyaluronic acid (Hylon) byinjection for a total of four times at intervals of 4 to 8 weeks. Theitching had already disappeared a few hours after the first injection.The keloid became considerably paler within two weeks and a flatteningwas already recognizable after four weeks. After ca. 6 months there wasa pale, only slightly raised scar.

Application example 2

The treatment of a keloid in the lower fold of the breast (right andleft) is described which occurred in a female patient after surgicalbreast correction.

The keloids were treated several times using conservative methods(topical preparations) and repeatedly excised. After the last excision,cross-linked hyaluronic acid was injected during the operation into thewound edges on the right side. Then both sides were sutured identically.The sutures were removed on the right and left side after two weeks.After four weeks the untreated scar on the left side was raisedconsiderably more and was more reddened than the scar on the right sidetreated with hyaluronic acid. In addition it was possible tosuccessfully prevent the reoccurrence of a keloid on the right-handside. This also demonstrates the preventive effect of the pharmaceuticalpreparation according to the invention.

I claim:
 1. A method for treating a pre-existing scar or pre-existingkeloid comprising injecting a composition comprising a pharmaceuticallyeffective amount of a cress-linked hyaluronic acid in combination with apharmaceutically acceptable carrier into the pre-existing scar orpre-existing keloid, wherein the pharmaceutically effective amount of across-linked hyaluronic acid is 0.1% to 20% by weight of thecomposition.
 2. A method for treating a scar or keloid according toclaim 1, wherein said cross-linked hyaluronic is cross-linked bychemical cross-linking, chelate formation, complex formation or saltformation.
 3. A method for treating a scar or keloid according to claim1, wherein said cross-linked hyaluronic acid is cross-linked by chemicalcross-linking.